The artificial capillary culture technique provides a pericellular microenvironment that closely resembles the in vivo state. This may allow normal cells to maintain their differentiated functions for prolonged periods of time in vitro. Cells are maintained in a physiologic state without many of the artifactual conditions imposed by more standard methods of tissue culture. The technique is, therefore, especially well suited for the culture of cells both of endocrine origin and their target cells. Response of cells to various hormones and their culture over long periods have been achieved thus making the techniques useful for continuous production of hormones for both laboratory and clinical uses. Modifications have been made to the basic design. These permit study of nutrient and product transport through the tissues formed in the intercapillary spaces, the effect of lymphatic-type drainage upon cell function, and effects of a physiologic collagen sub-stratum upon cell growth.